The invention pertains to a suspension attaching a mower-conditioner header or platform on a mobile frame by means of at least one lower link and one upper link, each of which is vertically pivoting.
U.S. Pat. No. 3,780,506, granted to Tashiro on Dec. 25, 1973, discloses a mower-conditioner having a cutter bar incorporated in a header or platform which is suspended on a frame, in a vertically pivoting manner, by means of one lower link and two upper links. The upper links are each moved up and down by means of a hydraulic cylinder and are each biased upward by means of a spring. If, during operation, the cutter bar slides along the ground and hits an obstacle, it raises and tilts forward, since the hydraulic cylinders are then not pressurized so that the header is free to float.
A mower-conditioner disclosed in U.S. Pat. No. 4,182,099, granted to Davis et al. on Jan. 08, 1980, has a cutter bar incorporated in a header which is mounted to a mobile frame by means of pairs of nearly parallel upper and lower links. Upon hitting an obstacle, the cutter bar may yield upward only under certain conditions and, otherwise, fully receives the impact.
The underlying problem of the invention is found in the fact that the known suspensions are hardly suitable to protect the cutter bar from sharp impact when hitting an obstacle.